This registered
cover was sent from Harbin.
Harbin is over 700 km northwest of Vladivostok.
At the time Manchukuo was a puppet state of Japan.

Harbin is where the
the Chinese railroad
running north from
Beijing joins the Trans Siberian Railway between Cita and Vladivostok.
It is easy to understand why the cover was routed VIA SIBERIA.

The cover was neatly
typewritten in the Royal
Danish
Consulate who marked the cover Registered.

The cover has an
interesting prenumbered
registry label that
required a boxed HARBIN 2 handstamp to provide the city.

The cover was
franked with two 1936 orchid
crest
stamps - a 2 fen light green and am 8 fen ocher (Scott 75 and 77).
There is also a 1936 10 fen blue Communications Building at Hsinking
and a 6 fen carmine rose wild goose over the sea of Japan from the
issue commemorating the postal convention with Japan (Scott 81 and 82).

There are two
indistinct Harbin CDS.

The destination was
Tantah or Tanta.*
Tanta is in the Nile Delta about 90 km north of Cairo and 120 km
southeast of Alexandria.

It received an
AMB.[ulant] TARVISIO
VENEZIO GUILIA [choose
the English link(?)] CDS on
August 13.*
This is the railroad transit mark applied at the transfer point for
mail incoming from Austria.Tarvisio
[drag mouse across
the mountain range picture] is in the northern Alps lying between Italy
and Austria.

On August 14 it
received a Brindisi Transit
registered cancel.

Its next mark was
from Alexandria where it
arrived on August 18.
The Alexandria CDS notes FOREIGN.
The Tanta receiver is also dated August 18.

*Thanks to Mauro
Mowszowicz for identifying
Tarvisio.
His suggestion that it was the transfer point for mail between the
Austrian
and Italian postal systems led to an understanding of the whole cancel.
Thanks to Anne Burson-Tolpin for these comments and links about the
cover:

'The 1911 edition of the Encyclopedia
Britannica notes [Tanta's] 'central position nearly
midway
between the two main branches of the
Nile'--it was the 'converging-point of several railways traversing the
Delta in all directions. It has a population (1907) of 54,437, is the
capital of the rich province of Gharbia,' and has 'a large railway
station.' The Alexandria-Tantah leg of the cover's journey would have
been a quick hop, skip, and a jump.

"I couldn't track down either the sender or the receiver, but the
College St. Louis was a secondary school run by the Society for African
Missions (Societas Missionum Afros), a secondary college. Google isn't
giving anything current about it, so it may well have been closed after
the revolution in 1953. But that's just speculation."